Hi All,

Which crank has the longer stoke, the 997 Cooper crank or the 1098 crank? Odd question I know but would like to know.

Many thanks.

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63 Morris Cooper.
UK Mini van.

997 - 81.28 mm
1098 - 83.72 mm

http://en.wikipedia.org/wiki/BMC_A-Series_engine

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did I tell you that I won a trophy?

1098 Cranks have the longest "standard" stroke of all A series engines.

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DID I MENTION THAT I AM THE BEST SUPPLIER FOR MINI ELECTRICAL PARTS AND REPAIRS?
"Let us remove your "SHORTS"

997 stroke is much the same as a 1275.
I had a 997 motor (back when I was an apprentice) with a 1098 crank in it, we had to machine the tops off the pistons to get them below flush.

A 997 crank had a reputation for being `weak', but I don't see how it was weaker than a 1098- it had all the same dimensions except a slightly shorter stroke. Material (EN16) was identical.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

Many thanks to all who have responded.
Dr Mini, to fit the 1098 crank in your old 997, did you use 1098 rods & did you have to machine or modify the gearbox to clear the crank?

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63 Morris Cooper.
UK Mini van.

I kept the 997 rods (which are same as 850 ones, with split little end & clamp bolt).
I can't remember now if we had to mod the gearbox, it was back in 1964... but it would just about have cleared it I'd say.
These days I would use 998/1098 rods, the floating little end is stronger.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

so what size did that make it??
What was it like compared to other engines?

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Tim
Dusk Blue
1964 850

Pistons were 997 Cooper +.030", with a 1098 crank it was 1058cc.
Cam was a Waggott 18/58, it ran a big ported Deluxe head, twin Amal Monobloc 1-3/16" bike carbs (off a Triumph Bonneville?) and a Sonic LCB.
It was pretty quick for what it was, back then in the days of 850s and 997 Coopers.
It went even harder 2 years later when I bored it to 68mm, fitted a new 1098 crank & rods, Imp pistons, a 544 cam, ported 1275 head and twin HS4s...

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.